Optional modulators are solid state micro devices, which are widely used for microdisplay projection and other optical signal processing systems. Optional modulators can control or modulate an incident beam of light in a defined spatial pattern. The defined spatial pattern is correlated to a series of electrical inputs of image to the devices, through which the incident light beam can be modulated in intensity, phase, polarization or direction.
Two of the most commonly used classes of optical and particularly, spatial light modulators employ microelectromechanical system (MEMS) devices in a two dimensional array configured to provide two-dimensional modulation of incident light: Digital Micromirror Device (DMD) from Texas Instruments and the Grating Light Valve (GLV) device from Silicon Light Machines.
The appeal of the DMD has been evidenced in the widespread adoption, given its high optical efficiency, large etendue, wide bandwidth, high modulation speed and digitalized control algorithm for time sequential color combination and management. Despite its success in projection display applications, however, the DMD has been recognized with certain shortcomings, such as high power consumption per pixel, particularly for high resolution microdisplay projection applications in cellphone and handheld devices.
The GLV array devices based in fine reflective metal grids are also recognized with significant appeal in etendue, analog grey-scaling, optical efficiency, modulation speed and particularly, power consumption per pixel. However, the wavelength dependency under a digitalized control algorithm and incident angle sensitivity due to diffraction are evident on the GLV devices disclosed in the prior art. Particularly for microdisplay projection applications, digitalized spatial modulation is desired for modulating illumination of wide incident angle over visible spectrum and in particular, in association with time sequential or spatial mosaic pattern color management schemes.